This study is designed to discern if the use of a lumbosacral orthesis (LSO, also call a back support) improves the short-term outcome of lower back pain. participants will receive standard care (physical therapy, physician treatment), with one group also receiving an extensible LSO, and another group receiving an inextensible LSO. The inextensible LSO has been shown to increase stiffness of the trunk in individuals while wearing it. The hypothesis is that the group wearing the inextensible LSO will have improved outcomes over the other two groups (standard care or standard care plus the extensible LSO).